Heat pumps and hydrogen fuel cells

[sarahjmg4]

We’re doing a big refurb on an old, grade 2 listed farmhouse. It currently has no plumbing, although it is connected to mains gas. We’d love to make it as eco-friendly (and cheap to run!) as possible and I’m wondering if anyone with a similar type of house has any experience of air/ground source heat pumps? And pairing them with solar panels for electricity?

We’re planning to fit lots of roof insulation, desperately hoping we’ll be allowed to fit heritage double glazing (windows are falling apart anyway and will need to be refurbished/reglazed at least) and we think we’ll be able to do underfloor heating for about half of the house, but we’re aware we will be limited with what we can achieve in terms of air tightness. Are we fighting a losing battle here? Anyone with a similar sort of house got any experience with heat pumps? Has your electricity bill gone up a lot in order to run it? Could it be run off solar panels instead?

If we really don’t think renewable is an option for us, we’re looking at the idea of a hydrogen fuel cell boiler instead. It’s not renewable, as it uses mains gas to create hydrogen, which it uses to generate electricity and then the waste heat from that to heat the house, but overall it’s lower carbon than gas and electricity separately. Can anyone share any experience of using these?

Or any other renewable/low carbon heating method I’ve not come across?

Thanks

[JoMumsnet]

We're just bumping this thread for you, @sarahjmg4 - hopefully some Mumsnetters will be along soon to answer your questions.

[JungeTraktoristin]

@sarahjmg4

We have a 16th c farmhouse in the rural SW. We abandoned the idea of ground source, because we were advised by the council’s conservation officer that they would not look favourably on any plan that involved us lifting the floor slabs (we have giant flagstones throughout most of the ground floor). And logistically and financially it woukd probably be impossible anyway.

I haven’t abandoned the idea of an air source pump, but rough calculations suggest it would only ever be an adjunct to heating by boiler, so we will review when the oil boiler needs replacing (mains gas not an option). At that point I will also look into a wood pellet burner. Some people around here have wood boilers that take standard logs, but you need a lot of woodland and lots of labour to be self-sufficient in fuel - these people also tend to have quite chilly houses...

We currently have 4kw of solar PV panels combined with a solar diverter that feeds surplus power back into the water heating system. The panels have probably halved our electricity usage, and will make a small dent in the oil usage. We could put another 3kw of panels on the shed, but unless we also installed a battery it’s probably not worth it at the moment, though it’s an option for the future.

We have a thermal store instead of a standard hot water tank which could theoretically be connected to one of our wood burning stoves, and I’m going to talk to the plumber about that after Christmas.

I’d be wary of setting up any system where the technology is still a bit beta, or that is so complicated that mainstream plumbers or boiler engineers won’t understand it - that includes thermal stores fwiw. Also I’d suggest taking your time and living in the house for a bit before you make drastic changes, just to get a feel for how the house works and how you want to live in it.

[sarahjmg4]

Thanks for your thoughts and advice. Unfortunately living in it isn’t really an option (it’s borderline derelict......no kitchen, no bathroom, I can see the sky through the roof and it’s structurally questionable, being held up by struts in places!).

I guess we’re at the mercy of the planners a little too. It’s a difficult decision, we want to ‘future-proof’ it a bit as well, but equally we need the heating to work!

I have a company called ISO Energy coming to have a look and they specialise in heating properties like this, so I’ll see what they have to say.

If not the hydrogen boiler could be an option. It’s very new, but sounds like the components have been designed to fit like a mainstream boiler and it would at least cut down on the amount of fossil fuels we use.

Thanks again

[Thehagonthehill]

If it's grade 2 you may not be allowed to put solar panels on the roof.

[sarahjmg4]

We have got an option for a ground mounted array instead if need be, although I’m not sure how they fare against eg flying footballs etc!

[JungeTraktoristin]

Ah ok, if it’s not currently habitable then you have the opportunity to do something more radical. If we were starting from scratch and had the opportunity to go for ground source I’d definitely be interested in that. The problem with running the pump from the solar is of course the same problem inherent to any solar system, which is that you need the energy the most at the point where the system is producing the least. So you’d need a battery, which is another £6k.

But if you get the right configuration for your needs it could definitely work - Our neighbour has just had an installation of 7kw of panels linked to a Tesla powerwall, and they are v happy with it. But they run an electric car and a couple of commercial ovens, so their needs are different from ours.

A listing is not necessarily a bar to solar panels - we have a valley gutter between two pitched roofs, so the panels are on the inward-facing slope and can’t be seen from the ground. But we definitely wouldn’t have been allowed to put them on the front-facing roof slope, so it depends on your set-up.

Getting specialist advice can only be a good thing, but I would reiterate my warning about investing too much in a system without a proven track record, or which is excessively complicated. We inherited a very over-complex solar thermal system when we bought the house which nobody entirely understood and nobody could quite fix, because it was too idiosyncratic. Companies are keen to convince you of their exciting new solutions, which is all very well until it goes wrong and no local plumber knows how to fix it. They you have to pay £££ for someone from the original company to come and do a survey and write a report saying it’s all fine really, except it clearly isn’t because the radiators still don’t heat up properly.

[sarahjmg4]

That is a very good point. I considered a wind turbine too, but I think we’re just not exposed enough (and if solar is hard to get through planning, a wind turbine would be impossible!).

Does your neighbours system run a heat pump too? We won’t have commercial ovens, but an electric car is on my list as soon as the house is done! Did they seek advice from a specialist before fitting it all? If so, any idea who they were (I think you said you’re SW and I’m in Gloucestershire, so maybe they’re not too far away). I have a company called ISO energy coming to have a look and they look promising. They specialise in renewable energy for old buildings like this and have worked on listed building too.

That sounds very similar to ours. It’s 3 storeys with a double pitched roof and the rear is south facing, so I’m hoping they’ll allow them there and on an outbuilding and garage. Failing that, the way the driveway curves means there’ll be a patch of land that’ll never get used, so that could work too. I’m hoping the fact it’s derelict will work in our favour a bit, maybe it’ll give us some leverage with the planners to get a few more aspects approved.

Overall though, keep it simple.....makes perfect sense

[JungeTraktoristin]

I think the neighbours do have an air source pump, but they had that before they installed the panels. I don't know who they used - we used a company called Solarsense based in Bristol, who were very good. They do the solar for Worthy Farm and Glastonbury festival, so I took that as a recommendation... A 4 kw solar array with inverter and Apollo solar diverter was about £5k (no battery). We will be looking to get an electric car in the future but at the moment I still do a reasonable proportion of long journeys for kids at university etc which just wouldn't be realistic with a mid-range electric vehicle.

I looked briefly at turbines but a quick search on a site that calculates average wind speed by postcode indicated that it's not windy enough to make it worthwhile. Another one of our neighbours does have a turbine, but I suspect it's a diy job from the early days of alternative power - people use them to power free-standing pumps for water troughs etc, but I doubt it would make a significant contribution to domestic electrical usage.

Think carefully about how you use the power, as that will determine the decisions you make. My neighbours with the ovens and the electric vehicle need to use power outside main daylight hours as they have to fire up the oven at night time and charge the car overnight as well, so the battery makes sense for them. We mainly work from home, so can run appliances in the daytime and could charge a vehicle in the day as well, so at the moment the benefit of a battery would not outweigh the cost. If we fit an airsource pump at some point in the future, that equation might change.

But yes, keep it simple is a good watchword. If the manufacturers/suppliers can't explain to you how it works in terms that you can understand, be sceptical. Find a friendly local plumber/builder/electrician and see if it makes sense to them and whether they would be prepared to work with it if things needed changing or repairing.

Once you're looking at specific systems, there'll almost certainly be a Facebook users' group for it, where you can get a sense of how it's working for actual people in the real world outside the manufacturer's shiny brochure. Have a look at the Everhot Cookers discussion group to see this kind of thing done well - it's mainly people burbling at length about how much they love their cooker, but occasionally there's a problem and people offer solutions and then the chap from Everhot pops up on the thread to give advice. There are also lots of FB groups for sustainability and self-sufficiency, so you might find more detailed discussions of the relative merits of different setups on there.

Going back to your OP, you should be ok with double-glazed windows as long as you fit ones that are acceptably slim in profile. Buildingconservation.com is the website recommended to us by the Council's conservation department for sourcing reputable tradesmen for listed buildings. 'Like for like' is the key term to use in any application for listed building consent (assumign that's vaguely true of course).

They tend to look favourably on works that are likely to make the building more sustainable, as long as they don't radically change the appearance. If you do want to do something more drastic, they tend to prefer schemes that are obviously modern and contrasting with the existing building - what they really hate is anything that looks like pastiche. So a glass box conservatory might get the go-ahead, but upvc Victoriana notsomuch.

[sarahjmg4]

Thanks so much for your help. That Facebook user group is a great idea, I might see if I can find one or two and gather some more info!

Not heard of Everhot, I’ll have a look.

Yep, that’s our plan. We’re hoping for a small extension to create a bigger kitchen and we’re making itma complete contrast with a wildflower green roof too!

Again, thanks so much, I really appreciate your help